Component alignment is of critical importance in semiconductor laser system and/or MOEMS (micro-optical electromechanical systems) manufacturing. The basic nature of light requires that light generating, transmitting, and modifying components must be positioned accurately with respect to one another, especially in the context of free-space-interconnect optical systems, in order to function properly and effectively in electro-optical or all optical systems. Scales characteristic of semiconductor and MOEMS can necessitate micrometer to sub-micrometer alignment accuracy.
Consider the specific examples of coupling light from a semiconductor diode laser, such as a pump laser, to a core of a single mode fiber or coupling light into and out of a semiconductor optical amplifier (SOA). Only the power that is coupled into the fiber core is usable to subsequent system, such as a fiber amplifier or a detector in the case of an SOA. In the context of the SOA, input light must further be focused onto an input facet to provide a signal to be amplified.
One alignment technique that has been proposed for free-space-interconnect optical systems is to mount lenses on deformable mounting structures. Such systems enable the semiconductor laser system to be constructed and then later aligned to maximize coupling efficiencies.
One problem that arises with these proposed mounting structures is that they do not provide for alignment in the direction of the optical axis. Typically, they are configured such that they are deformable in a plane that is perpendicular to the optical axis. This is useful for many forms of alignment where the axis of the beam must be vertically and horizontally aligned relative to the optical bench on which the structure is installed. Additional degrees of freedom, however, are required when controlling the cross-sectional characteristics, such as when focusing the beam to couple it into a semiconductor chip or tunable filter.
In general, according to one aspect, the invention features a mounting and alignment structure of an optical component. The structure has an optical element interface. Optical elements, such as lenses or fibers are attached to the mounting structure at this interface.
The structure further comprises a base. The base forms the part of the structure that is generally attached to an optical bench or other submount, for example. Armatures extend between the base and the interface to allow for deformation or alignment of the optical structure in a plane that is orthogonal to an optical axis.
According to the present invention, the base further includes an upper support, a lower support, and a link extending between the upper and lower support.
In the preferred embodiment, this link allows the mounting structure to be deformed in a direction at least partially parallel to the optical axis. Thus, when a lens optical element is mounted on the mounting structure, for example, a position of the focal point of the beam being transmitted through the lens can be controlled in a direction of the optical axis.
In a preferred embodiment, two links are provided, each extending between the upper support and the lower support. One of these links is on a proximal side of the structure and the other is on a distal side of the structure.
In the present embodiment, these links form a hollow tubular flexion. The axis of this flexion extends in a direction parallel to the bench to which the mounting and alignment structure attaches, and in a direction that is orthogonal to a plane that is perpendicular to the bench and passes through the optical axis.
In general, according to another aspect, the invention also features a method for manufacturing a mounting structure of an optical component. This method comprises patterning a base resist layer to form a foundation mold for the optical element interface, at least one armature, and a portion of the base. This foundation mold is then filled with bulk material. A link resist layer is then patterned and developed to form a link mold on the bulk material. This link mold is then filled with bulk material to form an additional portion, or link, of the base.
In the preferred embodiment, a second link mold is further made and filled to form a second link.
Preferably, the system utilizes the LIGA process. LIGA is a German acronym for lithography, plating, and molding. Specifically, the foundation resist layer is usually PMMA. It is exposed using X-rays from a synchrotron, for example. The resist layer is then later developed and filled, using a plating or electroforming process with a nickel or gold bulk material.
In general, according to still another aspect of the invention, a method for positioning a mounting and alignment structure on optical bench is featured. This comprises forming a mounting structure comprising a component interface, at least one base, and at least one armature connecting the component to the base. An optical component alignment feature is formed on the base of the mounting structure. Further, a bench alignment feature is formed on the bench. The mounting structure of the optical bench is then mated to the component alignment feature.
The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.